The Neuroanatomy Core will provide both light and electron microscopic services to the Projects, including tissue staining, sectioning and imaging. Ten aims in three projects will utilize this Core facility. Projects 2( Rosenberg) and 3 (Saper) will use the Core for in situ hybridization histochemistry to localize mRNA for phosphodiesterases, adenosine receptors and glutamic acid decarboxylase in rat brain, and the latter also in human brain. Light microscopic immunocytochemical services will be used by Project 2, 3, and 4 to localize cholinergic neurons, as well as immunocytochemistry for neurons containing enkephalin, in some cases combined with retrograde tract tracing or in situ hybridization methods. Electron microscopic immunocytochemistry will be used by Project 4 to examine the chemical specificity of afferents to hypoglossal motor neurons. The centralization of these services in one laboratory will give the laboratories that do relative little neuroanatomy (Rosenberg and Greene) access to the technical proficiency of the Core laboratory and staff and will allow economy of scale in order and using reagents, isotopes and photographic emulsion.